KR101162781B1 - Method and apparatus for reducing transmitted energy in power-controlled systems based on early decoding - Google Patents

Abstract

The present invention provides a method of reducing the transmitted energy based on early decoding. The method includes accessing a first portion of a block that includes a plurality of symbols representing an encoded message. The first portion was transmitted at the first transmit power and is less than all the plurality of symbols. In addition, the method further comprises the steps of attempting to decode the encoded message using the first portion of the block, determining if the encoded message has been decoded, determining if the encoded message has been decoded, and whether the encoded message has been decoded. Providing an indication of the second transmit power in response to the determining.

Description

METHOD AND APPARATUS FOR REDUCING TRANSMITTED ENERGY IN POWER-CONTROLLED SYSTEMS BASED ON EARLY DECODING}

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood with reference to the following description in conjunction with the accompanying drawings, wherein like reference numerals refer to like reference elements.

1 illustrates a wireless telecommunication system in accordance with the present invention.

2A conceptually illustrates a message that may be encoded for transmission over an air interface.

2B conceptually illustrates a block that may be transmitted over an air interface.

2C conceptually illustrates a decoding message.

3 conceptually illustrates a method of controlling transmit power based on early decoding of a portion of one or more received blocks.

4A conceptually illustrates the transmit power level during a first embodiment of a power down sequence and a power up sequence associated with the transmission of a block.

4B conceptually illustrates the transmit power level during the second embodiment of the power drop sequence and power rise sequence associated with the transmission of the block.

Explanation of symbols for the main parts of the drawings

105: mobile unit 110: base station

125, 150 transmitter 130, 155 receiver

135, 165: encoder 140, 170: decoder

145: mobile unit controller 175: base station controller

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are described herein in detail with reference to the drawings. However, the description of specific embodiments herein is capable of all changes, equivalents, and embodiments within the spirit and scope of the invention as defined by the appended claims, without limiting the invention to the specific form.

The present invention generally relates to telecommunication systems, and more particularly to wireless telecommunication systems.

The transmit power used to transmit symbols over the air interface (eg, the air interface between the mobile unit and the base station in a wireless telecommunication system) is typically determined by balancing conflicting constraints. For example, increasing the transmit power can reduce the bit error rate (BER) associated with transmission over the air interface. However, increasing the transmit power also increases system interference between the mobile unit and / or base station. In addition, increasing the transmit power of the transmitter in the mobile unit can shorten the operating life of the battery in the mobile unit. Therefore, the transmit power can be chosen to balance constraints on low BER, low system interference and long battery life.

The optimal transmit power typically varies with time. For example, as the mobile unit moves away from the base station, it may continue to increase the transmit power of the transmitter at the mobile unit and / or base station to maintain proper BER even if the battery life is reduced or the system interface is increased. Therefore, a closed loop power control system can be used to control the transmit power of a transmitter in a wireless telecommunication system. In a typical closed loop power control system as may be implemented in a wireless telecommunication system operating in accordance with the CDMA 2000 and / or UMTS protocol, feedback information is sent from the receiver to the transmitter at regular intervals. For example, the transmit power associated with a slot in a frame can be controlled using a single power control bit that can be transmitted once per slot. The power control bits may instruct the transmitter to reduce or increase the power transmitted for the next slot in accordance with a signal-to-noise ratio (SNR) associated with the received signal, such as a pilot or traffic signal.

Coded transmissions using closed loop power control may use more power than necessary to achieve the desired performance. Inefficiencies in a closed loop power control system may be due to insufficient transmission moment characteristics of the instantaneous channel fluctuations of the wireless telecommunication system and / or causes such as step size at an acceptable level of transmitted power, delay in the power control loop, and the like. May result. Thus, closed loop power control can create an unnecessarily large system interface and reduce battery life.

The present invention will solve one or more of the problems described above.

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an exhaustive overview of the invention. It is not intended to be exhaustive or to limit the scope of the invention or the essential components of the invention. The sole purpose of the summary is to present a simplified form of some concepts as a prelude to the more detailed description that is discussed later.

In one embodiment of the present invention, the method provides a method of reducing the transmitted energy based on early decoding. The method includes accessing a first portion of a block that includes a plurality of symbols representing an encoded message. The first portion was transmitted at the first transmit power and is less than all the plurality of symbols. The method also uses the first portion of the block to attempt to decode the encoded message, determining whether the encoded message has been decoded, and determining whether the encoded message has been decoded. Providing an indication.

Exemplary embodiments of the invention are described below. In order to clearly describe the present invention, not all features of the current implementation are described in the specification. Of course, in developing such a practical embodiment, numerous implementation-specific options, such as system-related compatibility and business constraints, that vary from implementation to implementation, must be determined in order to achieve the developer's specific goals. Moreover, such development efforts will be complex and time consuming, but nevertheless, one of ordinary skill in the art will be able to practice using the disclosure.

Portions of the invention and corresponding details are set forth in symbolic representations operating on software or algorithms and data bits in computer memory. Those skilled in the art will effectively convey the substance of their work to others skilled in the art with these descriptions and representations. The term algorithm, as used herein, means a series of coherent sequences that, in a conventional sense, yield a desired result. These steps are those requiring physical manipulations of physical quantities. Typically, although not required, these quantities take the form of optical, electrical or electronic signals that can be stored, transmitted, mixed, compared and otherwise manipulated. Occasionally, it was recognized that it is convenient to refer to these signals as bits, values, elements, symbols, letters, terms, and numbers.

However, it should be borne in mind that terms similar to all of these relate to suitable physical quantities and are merely convenient name tags applied to these quantities. Unless otherwise stated or as apparent from the description, terms such as "process" or "operation" or "determination" or "display" refer to data in computer system memory or in physical and electrical quantities within the registers and memory of the computer system. It refers to the operation and processing of a computer system or similar electronic computing device that manipulates and transforms into a register or other such data storage device, transmission device or display device that is similarly represented in physical quantities.

In addition, the software embodying the features of the present invention is typically encoded in some form of program storage medium or implemented on a transmission medium. The program storage medium may be magnetic (eg, floppy disk or hard drive) or optical (eg, small disk ROM or “CD ROM”) and may only be read or randomly accessed. Similarly, the transmission medium may be a twisted pair (TP) wire, coaxial cable, optical fiber, or other suitable transmission medium known in the art.

The invention will now be described with reference to the accompanying drawings. Various structures, systems and devices have been shown schematically in the drawings in order not to obscure the present invention because of configurations that are well known to those skilled in the art for purposes of illustration only. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present invention. The words and phrases used herein are to be understood and described as well as would be understood by those skilled in the art. The use of the term or phrase consistently herein does not mean a definition that is different from the conventional and customary meanings understood by those skilled in the art. Where a term or phrase differs from a particular meaning, ie, meaning understood by one of ordinary skill in the art, the term and phrase will be clearly and directly defined in the specification.

1 illustrates a wireless telecommunication system 100. The wireless telecommunication system 100 includes a mobile unit 105 and a base station 110. In various variations. The mobile unit 105 can be a mobile phone or any other predetermined device, including a personal computer, laptop computer, PDA, and the like. Moreover, in variations, the base station 110 may be an access point, a relay station, or the like. Mobile unit 105 and base station 110 communicate using wireless telecommunication link 115. In accordance with conventions in the art, the wireless telecommunications link 115 will be referred to below as the wireless interface 115.

Mobile unit 105 and base station 110 exchange messages over air interface 115 by various protocols. For example, mobile unit 105 and base station 110 may exchange messages by UMTS protocol, GSM protocol, or the like. However, mobile unit 105 and base station 110 are not limited to the protocol described above. In a variation, any preferred wireless telecommunication protocol may be used to exchange messages over the air interface 115. For example, the air interface 115 may operate according to a Bluetooth protocol, an 802.11 protocol, or the like. As will be appreciated by those skilled in the art, a message includes various signaling and / or data messages that may be sent in various types of frames or blocks. For example, the radio layer protocol includes a control frame, a data frame, a fill frame, and an idle frame.

The mobile unit 105 includes at least one antenna 120 coupled to the transmitter 125 and the receiver 130. Transmitter 125 is coupled to encoder 135 and receiver 130 is coupled to decoder 140, and encoder 135 and decoder 140 are coupled to mobile unit controller 145. In the illustrated embodiment, the transmitter 125, receiver 130, encoder 135, decoder 140, and mobile unit controller 145 are shown as separate components. However, one skilled in the art will recognize that the present invention is not limited in this way. In a variation, portions of the transmitter 125, receiver 130, encoder 135, decoder 140, and / or mobile unit controller 145 may be combined into a single element or integrated into another portion of the mobile unit 105. Can be. Moreover, mobile unit 105 may include other elements not shown in FIG. 1.

Base station 110 includes a transmitter 150 and a receiver 155 coupled to at least one antenna, such as radio station tower 160. The transmitter 150 and the receiver 155 are coupled to the encoder 165 and the decoder 170, respectively. Encoder 165 and decoder 170 are coupled to base station controller 175. In the illustrated embodiment, the transmitter 150, receiver 155, encoder 165, decoder 170, and base station controller 175 are shown as separate components. However, one skilled in the art will recognize that the present invention is not limited in this way. In a variation, portions of transmitter 150, receiver 155, encoder 165, decoder 170, and / or mobile unit controller 175 may be combined into a single element or integrated into another portion of mobile unit 105. Can be. Moreover, base station 110 may include other devices not shown in FIG. 1.

In operation, mobile unit controller 145 may provide a message to encoder 135 that may encode the message by any desired encoding algorithm, such as a Viterbi encoding algorithm. This encoding message includes one or more blocks or frames having a plurality of symbols. These symbols are then provided to a transmitter 125 that can transmit symbols over the air interface 115 using the antenna 120. In addition, the message may be received using the antenna 120 and the receiver 130. The received message is then provided to a decoder 140 capable of decoding the received symbol. For example, the received symbol can be decoded using a Viterbi decoding algorithm. Those skilled in the art will appreciate that the present invention is not limited to Viterbi encoding and / or decoding, and that in variations, preferred encoding / decoding techniques and / or algorithms may be used.

In addition, the base station 110 may transmit and / or receive a message. In the illustrated embodiment, the message to be transmitted is provided by the base station controller 175 and encoded by the encoder 165 and then the wireless interface 115 by the transmitter 150 using the wireless tower 160. Is sent through. The message may also be received by the wireless tower 160 and the receiver 155. The symbols of the received message can then be decoded by decoder 170 and provided to base station controller 175. As mentioned above, any predetermined encoding and / or decoding technique or algorithm may be used by the base station 110.

2A conceptually illustrates a message 200 that may be encoded for transmission over the air interface 115 by the mobile unit 105 or the base station 110. In the illustrated embodiment, the message 200 includes a plurality of bits 205 (1-n). For example, bit (205 (1) is a value of 1, bit (205 (2)) is a value of 0, bit (205 (3)) is a value of 0, and bit ((205) (n)) is set to a value of 1. For example, message 200 may be a block comprising 192 bits (205 (1-n)), then message 200 is a wireless interface. It may be provided to an encoder, such as the encoders 135 and 165 shown in FIG. 1 for encoding before being transmitted via.

FIG. 2B conceptually illustrates a block 210 that may be transmitted over an air interface, such as the air interface 115 shown in FIG. 1. In the illustrated embodiment, block 210 is formed of a plurality of symbols formed by encoding bits 205 (1-n) of message 200 shown in FIG. 2A using a 1 / m rate encoding algorithm. It includes. Thus, block 210 includes m · n symbols 215 (1-m · n) and dashes (−) indicate the range of values for the corresponding indexes. ) May be encoded using the 1/8 rate algorithm to include 8n symbols 215. Those skilled in the art will appreciate that the present invention is not limited to any particular rate encoder algorithm. ) May be encoded using a two-third rate encoder algorithm, and the symbols 215 of block 210 may then be transmitted over the air interface to other devices from which they can be decoded.

FIG. 2C conceptually illustrates a decoded message 220 that may be generated by the decoders 140, 170 shown in FIG. 1. In the illustrated embodiment, the message 220 includes a value of bits 225 (1-n) corresponding to bits 205 (1-n) in the message 220. Since the value of bits 225 (1-n) of the decoded message 220 corresponds to bits 205 (1-n) of the message 200, the decoding operation may be referred to as successful decoding. However, one of ordinary skill in the art will appreciate that the one-to-one correspondence between bits 225 (1-n) and bits 205 (1-n) is not the only criterion that indicates the successful decoder of block 210. For example, in some embodiments, a particular number of bits 225 (1-n) may not correspond to bits 205 (1-n) because of some error in encoding, transmission and / or decoding. However, a small number of errors can be determined to be not significantly significant so decoding can still be considered successful if there are a small number of errors in the decoded message 220. The exact number of errors considered insignificant is a matter of design choice but is not critical to the present invention.

1 and 2A-C, the mobile unit controller 145 and / or the base station controller 175 can determine the transmit power of the message transmitted by the transmitters 125, 150. The mobile unit controller 145 can provide an indication of the transmit power level to a transmitter 125 that can transmit a message at a nearly selected transmit power level. In various variations, the transmit power may be, for example, a low BER requirement for a block transmitted over the air interface 115, a low system interference requirement between the transmission over the air interface 115 and other transmissions of the wireless telecommunication system 100. , And opposing constraints, including the long life requirements of the battery, may be selected to balance battery operated devices such as mobile unit 105 in wireless telecommunication system 100.

Mobile unit controller 145 and / or base station controller 175 may change the selected transmit power level while block 210 is being transmitted over air interface 115 as it successfully decodes a portion of block 210. . In one embodiment, if decoder 170 successfully decodes block 210 based on a portion of block 210, then base station 110 causes the transmitter 125 to halve any remaining portion of the block. Instructing the power to be lowered and then raising the power for the last half of any remaining subsection of block 210 to move the transmit power level back to the desired value in preparation for the transmission of the next block. Send one or more bits to unit 105. The inter-power level can be driven as fast as possible without changing the power control signaling currently in use, so there is no need to change existing power control protocol standards. For example, decoder 170 attempts to decode first portion 215 (1-8) when base station 110 receives first portion 215 (1-8) of block 210. FIG. . As will be described below, if the decoder 170 successfully decodes the first portion 215 (1-8), the base station controller 175 may determine the next portion 215 (of block 210) at the reduced transmit power. 9-mn) may provide an indication of the reduced transmit power level to the mobile unit 105 capable of transmitting.

3 conceptually illustrates a method 300 of controlling a transmit power level based on early decoding of one or more block receivers, such as block 210 shown in FIG. 2B. In the following description, the method 300 will be described with reference to a transmitter, a receiver, an encoder, a decoder, a transmission controller and a reception controller. Those skilled in the art will appreciate that the method 300 may be implemented in any given apparatus capable of transmitting and / or receiving messages over the air interface. Thus, in various modifications, the transmitter, receiver, encoder, decoder, transmission controller and reception controller may be implemented in as many devices as possible. For example, the method 300 and the aforementioned components may be a personal computer, laptop computer, PDA, as described above. It may be implemented in one or more mobile units 105 and base station 110 as well as in access points and the like.

The transmitter transmits 305 a portion of the block at a first transmit power level that can be selected by the transmit controller. The block contains a symbol that indicates the bits of the message that were encoded by the encoder. The receiver receives 310 the transmitted portion of the block. For example, as described above, some of the blocks may be sent by the mobile unit and received by the base station. The decoder attempts to decode the received portion of the block (315) and determines (320) whether the received portion of the block has been successfully decoded. In one embodiment, the portion of the block that has not yet been received is treated as deleted. Those skilled in the art will appreciate that any predetermined method of determining whether a received portion of a block has been successfully decoded may be used.

If the received portion of the block has not been successfully decoded (315), the receiving controller can determine (325) whether a large portion of the block has been received or will be received. If the receiving controller is determined to receive or be received more (325), one or more additional attempts to decode the received portion may be determined (315). For example, a portion of the newly received block is first combined with the received portion of the block and the decoder will attempt to decode the combined portion of the block (315). If no additional portion of the block has been received or expected to be received, the method 330 terminates.

If the decoder determines that the block was successfully decoded based on the received portion of the one or more blocks (320), the transmitter will drop the power (335). For example, the block can be successfully decoded using only about one quarter of the symbols so that the transmitter can drop power while transmitting the remaining symbols (335). In one embodiment, power drop 335 includes a reception controller that provides a desirable message indication to power drop 335. The transmit controller reduces the transmit power level by a selected amount after receiving the message. For example, the message may be one or more bits each indicating that the transmit power should be reduced by a predetermined amount of increase. The power drop bit may be provided in one or more slots in a single block or multiple blocks. As another example, the message may be a power down message indicating that the transmitter should reduce its transmit power to a significantly lower level or to completely stop transmission.

In one embodiment, it may be desirable to increase the transmit power before transmitting the symbol for the next block. Therefore, the transmitter may raise power 340 near the dropping power 335. In one embodiment, the receiving controller may provide a message indicating that it is desirable to increase the power level after the charge is substantially terminated, and when the transmitter receives this message, the transmit power used to transmit the symbol in its response. You can increase the level. For example, the receiving controller may provide one or more bits each indicating that the transmit power level should increase by a predetermined amount of increase. As another example, the receiving controller may provide a power up message indicating that the transmitter should increase the transmit power level to the initial transmit power level or that the transmitter should resume transmission. In one embodiment, the transmit power level after power rise 340 may be substantially the same as the transmit power level before power drop 335. However, those skilled in the art will recognize that the present invention is not limited thereto. For example, the transmit power level after power rise 340 may be lower than the transmit power level before power drop 335. The method 300 may terminate 330 after a power up 340.

4A conceptually illustrates a transmit power level 400 during a first embodiment of a power down sequence and a power up sequence associated with transmission of a block. The vertical axis 405 represents the transmit power level, and the horizontal axis 410 represents the time elapsed while transmitting the block. However, one of ordinary skill in the art will appreciate that the horizontal axis 410 may also refer to a slot within a transmission frame. In the first embodiment shown in FIG. 4A, the receiving controller may provide a plurality of bits indicating that the transmit power level 400 should decrease by a predetermined amount of increase. The transmitter reduces the transmit power level 400 by a predetermined increase in response to receiving each bit. Thus, the transmit power level 400 decreases in a stepwise manner. As it nears the end of the block, as indicated by the vertical dashed line 415, the receiving controller may provide a series of bits indicating that the transmit power level 400 should increase by a predetermined amount of increase. The transmitter increases the transmit power level 400 by a predetermined increase in response to receiving each bit. Thus, the transmit power level 400 generally increases stepwise until reaching the same level as the initial value of the transmit power level.

4B conceptually illustrates transmit power level 420 during a second embodiment of a power down sequence and a power up sequence associated with transmission of a block. The vertical axis 425 represents the transmit power level, and the horizontal axis 430 represents the time elapsed while transmitting the block. However, one of ordinary skill in the art should also recognize that the horizontal axis 430 may represent a slot in a transmission frame. In the second embodiment illustrated in FIG. 4B, the receiving controller provides a power down message and the transmitter reduces the transmit power level 420 in response to receiving the power down message. Thus, the transmit power level 420 decreases to a significantly lower value. In one embodiment, the transmission is stopped. That is, the transmit power level 420 is reduced to approximately zero. As it nears the end of the block, as indicated by vertical dashed line 435, the receiving controller provides a power up message and the transmitter increases to an initial value of transmit power level 420 in response to receiving the power up message. .

By implementing one or more of the embodiments described above, it is possible to improve the efficiency of encoded transmissions while maintaining the desired performance of the wireless telecommunications system 100 shown in FIG. For example, system interference can be reduced and battery life can be increased while maintaining the desired BER.

The specific embodiments described above are merely exemplary, and the present invention may be modified or made in a manner equivalent to those skilled in the art while having the advantages taught herein. Moreover, there is no limitation on the details of the design or structure specified herein except as described in the claims below. Therefore, it is obvious that the specific embodiments described above can be changed or modified and that all such changes can be considered within the spirit and scope of the invention. Accordingly, protection is claimed in the claims below.

According to the present invention, it is possible to provide a method for reducing the transmitted energy based on early decoding.

Claims (10)

A method of reducing transmission energy between a first device and a second device in a wireless communication system, The first device accessing a first portion of a block comprising a plurality of symbols representing an encoded message, the first portion being transmitted at a first transmit power by the second apparatus and the plurality of symbols Has fewer than all symbols-wow, The first device attempting to decode the encoded message using the first portion of the block; Determining, by the first device, whether the encoded message has been decoded; In response to determining that the encoded message has been decoded, providing, by the first device, an indication of a second transmit power to the second device; A method of reducing transmission energy between a first device and a second device in a wireless communication system. The method of claim 1, Providing an indication of the second transmit power includes providing at least one bit indicating a desired increase or decrease in the second transmit power relative to the first transmit power. A method of reducing transmission energy between a first device and a second device in a wireless communication system. The method of claim 1, Providing the indication of the second transmit power includes providing a power down message. A method of reducing transmission energy between a first device and a second device in a wireless communication system. The method of claim 1, If it is not determined that the encoded message has been successfully decoded, the first apparatus further comprises accessing at least one second portion of the block, each containing fewer than all of the plurality of symbols; A method of reducing transmission energy between a first device and a second device in a wireless communication system. The method of claim 4, wherein The first device attempting to decode the encoded message using the first portion and the at least one second portion of the block; Determining, by the first apparatus, whether the encoded message has been decoded using the first portion and the at least one second portion of the block; In response to determining that the encoded message has been decoded using the first portion and the at least one second portion of the block, the first apparatus provides an indication of a second transmit power to the second apparatus. Further comprising the step of A method of reducing transmission energy between a first device and a second device in a wireless communication system. A method of reducing transmission energy between a first device and a second device in a wireless communication system, Providing, by the second device, to the first device a first portion of a block comprising a plurality of symbols representing an encoded message, the first portion being provided at a first transmit power and all of the plurality of symbols Have fewer symbols-W, In response to providing the first portion of the block, the second device receiving an indication of a second transmit power from the first device; Providing, by the second device, the second portion of the block to the first device at the second transmit power; A method of reducing transmission energy between a first device and a second device in a wireless communication system. The method of claim 6, Receiving an indication of the second transmit power includes receiving at least one bit indicating a desired increase or decrease in the second transmit power relative to the first transmit power. A method of reducing transmission energy between a first device and a second device in a wireless communication system. The method of claim 6, Receiving an indication of the second transmit power includes receiving a power down message and suspending transmission of a subsequent portion of the block in response to receiving the power down message. A method of reducing transmission energy between a first device and a second device in a wireless communication system. The method of claim 6, Receiving the indication of the third transmit power from the first device after the second device receives the indication of the second transmit power, Receiving an indication of the third transmit power includes receiving at least one bit indicating a desired increase in the third transmit power relative to the second transmit power. A method of reducing transmission energy between a first device and a second device in a wireless communication system. The method of claim 9, In response to receiving the indication of the third transmit power, providing, by the second device, the at least one portion of the block to the first device at the third transmit power—indication for the third transmit power Receiving a powering message from the first device; and In response to receiving the power supply message, the second device further providing an additional portion of the block to the first device. A method of reducing transmission energy between a first device and a second device in a wireless communication system.

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